Ultrasonic techniques are used in catheters for measuring tissue depth. Examples of prior art techniques are provided below.
U.S. Pat. No. 8,628,473, whose disclosure is incorporated herein by reference, describes an ablation catheter with acoustic monitoring that comprises an elongated catheter body. A distal member disposed adjacent a distal end and including an ablation element to ablate a biological member at a target region outside the catheter body. One or more acoustic transducers, each configured to direct an acoustic beam toward a respective target ablation region and receive reflection echoes therefrom.
U.S. Patent application publication 2011/0144491, whose disclosure is incorporated herein by reference, describes a directable acoustic transducer assembly for use in a medical insertion device (MID). In an embodiment, the assembly aims an acoustic signal in response to a sensed or detected force or load imposed on the MID. The directable acoustic transducer assembly includes a switch array and a plurality of directional acoustic transducer elements. The switch array responds to the force or load and activates the directional acoustic transducer elements closest to the source of the force or load. The switch array may include a plurality of switches, at least one of which responses to a force or load and may activate directional acoustic transducer elements having a target tissue in the field of view.
U.S. Patent application publication 2011/0028848, whose disclosure is incorporated herein by reference, describes a device for measuring a spatial location of tissue surface, such as the interface between different types of tissues or between tissue and body fluids. The device includes an elongate catheter body having a distal end portion, a plurality of localization elements carried by the distal end portion, and at least one pulse-echo acoustic element carried by the distal end portion.
U.S. Pat. No. 8,545,408, whose disclosure is incorporated herein by reference, describes an ablation system that comprises a catheter including a pulse-echo ultrasonic transducer disposed in a distal portion and arranged to emit and receive an acoustic beam. The transducer emits and receives acoustic pulses to provide transducer detected information regarding the targeted tissue region being ablated. A rotation mechanism rotates at least the distal portion around a longitudinal axis of the catheter. A control and interface system processes the transducer detected information and provides feedback to a user via a user interface and/or the control and interface system to be used to control ablation.
Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.